The DNC has blocked Sanders’ access to the data “until it provides an explanation as well as assurances that all Clinton data has been destroyed,” the report says.

The Sanders campaign accused the DNC of playing favorites on Friday at an afternoon press conference and vowed to take the DNC to federal court to prevent the group from blocking its access to the database.

The incident will likely surface during the Democratic Party’s third debate Saturday in New Hampshire. Clinton holds a 20-point lead in national polls over Sanders, her nearest competitor, according to USA Today.

Jeff Weaver, the Vermont senator’s campaign manager, blamed the occurrence on a software vendor hired by the DNC for allowing access. But he acknowledged that a staffer was fired over the incident.

Having his campaign cut off from the national party’s voter data is a strategic setback for Sanders — and could be a devastating blow if it lasts. The episode also raises questions about the DNC’s ability to provide strategic resources to campaigns and state parties.

Sanders spokesman Michael Briggs said four Sanders campaign staffers accessed Clinton data, and that three of them did so at the direction of their boss, Josh Uretsky, who was the operative fired.

Uretsky told CNN Friday morning that he and others on the campaign discovered the software glitch Wednesday morning and probed the system to discover the extent of their own data’s exposure. He said there was no attempt to take Clinton information but said he took responsibility for the situation.